Three different aspects of this project are currently underway: (1) Studies of membrane damage by complement using resealed erythrocyte ghosts have concentrated on possible explanations for the heterogeneity of functional membrane pore sizes. Increasing complement dose allows efflux of larger markers from ghosts; varying the C8/C9 ratio by using a reactive lysis system in which individual components are added suggests variations in this ratio may explain some of heterogeneity. (2) Large unilamellar liposomes were made with radioactive markers trapped inside, and a technique based on immunoprecipitation developed to separate liposomes from released marker. Sieving by low detergent concentrations, seen previously in ghosts, was confirmed in this system. (3) To test the hypothesis that cytotoxic T lymphocytes lyse their target cells by causing membrane damage, techniques for creating planar lipid bilayer membranes contaning H-2 antigens are being developed. H-2 antigens were purified by affinity chromatography using hybridoma anti-H-2 antibodies and reinserted into liposomes.